The installation of stair handrails has always included a variety of methods. Early construction included the use of joinery or joints similar to that of furniture construction. Puzzle-like joints were cut into the joining surfaces thereby fitting together as a key fits a lock. Hardware was later designed and most connections were done by a series of spline nails and wood glue. As structural safety requirements increased, newer hardware dedicated to the fastening of handrails and fittings, hanger bolts, washers, and nuts were adapted to these fastening points.
Connection of two wooden stair products, such as handrails, has in some fashion been performed by drilling a channel in one end of one of the handrails to accept a bolt. The bolt is then inserted into the channel of the handrail. The exposed lag end then becomes the “male” end of the connection. A channel is then drilled in the end of the second handrail to accept the “male” end of the bolt. A hole is then drilled in the bottom of the second handrail to facilitate the fastening operation. With the channel drilled, the installer is then able to slide the “male” end of the handrail into the channel of the second handrail. Using the hole in the bottom of the rail, the installer is then able to insert the washer and nut and use a wrench to tighten the nut and pull the two handrails together. In the original rail bolt systems, standard steel flat washers were used. These washers would secure upon the initial tightening, but if flexed from a side load would loosen a connection and cause a failure in structure.
Washers of a similar nature were later constructed of polyethylene plastic with a semicircular or half concave design. These washers were an improvement from original steel flat washers that would often bind during installation. Polyethylene plastic washers fit the inside shape of the hole that was drilled into the rail to establish a more firm connection. Issues with the plastic structure, however, included the failure of structure with high levels of torque, and the susceptibility of the washer to align off center inside of the hole in the base of the handrail.
Although there are several fastening systems currently on the market none have all of the desired features such as easy installation, alignment capabilities and stability when structural forces are applied.
For example, U.S. Pat. No. 5,095,668 (the 668 patent) by O'Brien describes and claims a fastening system for fastening a newel post to the floor. Although the 668 patent describes using a rail bolt, a washer and a nut, there are several distinguishing aspects. The newel post in the 668 patent is positioned perpendicularly to the floor creating a joining surface on a horizontal plane with the floor. The post sits on the solid support of the floor that is located directly beneath the post thereby giving the horizontal connecting surface stability and strength from downward forces.
The fastening system of the present invention, however, is for a vertical joint where handrails are set on spatially separated posts and the joint is not directly above any post. Downward forces on the rails create instability rather than the additional stability of the 668 installation. Additionally, the joint of the present invention may have an angular aspect if used on a staircase and that would increase the unwanted forces, specifically the side lateral loads.
Other differing factors between the 668 patent and the present invention include the alignment problem of adjacent handrails. The 668 system is for a vertical post attached to the floor while the present invention is for adjacent railings (and/or fittings and/or a system of fittings) that need to be properly aligned to appear as a single, level rail. The ability to align rails is not addressed by the 668 patent.
The washer disclosed by the 668 patent does not provide the strength and aligning characteristics of the washer of the present invention. Nothing in the 668 patent suggests the use of a washer that provides pivoting capabilities to align adjacent members.
Similarly, the rail bolt kit distributed by Staircrafters Plus (rail bolt kit N-3079) and manufactured by L. J. Smith Stair Systems does not contain a washer having the required pivotal characteristics nor does the kit disclose the need for such characteristics to facilitate alignment of handrails. The washer in the Staircrafters kit is flat on one side and, therefore, is not capable of allowing the pivoting action of the desired fastening system.
Additionally, the bolt in the N-3079 kit and in the 668 patent does not have the precision characteristics of the bolt of the present invention. The design of the bolt and integration of the thread types, thread lengths and number of threads on the bolt and the types of bolt endings provides for additional strength characteristics and ability to position the fitting and rail such that the desired alignment is obtained.
In general, the approach of the art has been to focus on a particular aspect and none of the above-described fastening systems found in the prior art have been able to adequately provide the easy installation, alignment capabilities and strength desired for handrail installations. It would, therefore, be a significant advancement in the art to provide an improved aligning and fastening system that provides all of these features.